This invention relates to a phase-switched power supply having a filtered alternating current output.
In regulated alternating current power supplies, it is often desirable to control the output voltage by phase dependently switching the input alternating current on and off by means of some switching means (e.g. SCRs or transistors). This results in a non-sinusodial alternating current. This output is adequate for applications where output waveform, transient reduction and ride through are of no importance. Lighting and heating loads are typical alternating current phase control applications.
Another approach to supplying regulated alternating current is to use a ferroresonant transformer. This approach uses a saturating transformer with a resonance capacitor to provide a constant voltage, sinusoidal output (i.e. adequately sinusodial). Large amounts of capacitive volt-amperes circulate in the tank circuit to drive the secondary section of the core into saturation. This core saturation and the large circulating volt-amperes increase transformer size and losses compared to unsaturated operation.